By default, Microsoft Outlook will prevent you from opening certain file attachments that can damage your computer, e.g. by containing malware code. However, sometimes you need to be able to handle these attachments. 5star Outlook Antiblock offers you the ability to easily decide which file attachments you can trust, by managing the file extensions for the blocked attachments. And the best of all: This software is freeware! Compatible with Outlook 2000 to 2003.